1. Field of the Invention
This invention is related to instant messaging using protocols such as SIP (Session Initiation Protocol) and MSRP (Message Session Relay Protocol), and more particularly to the storage of SIP and MSRP messages as encapsulated MSRP messages.
2. Description of the Related Art
SIP instant messages can be sent to users, whether or not the user is online. A SIP MESSAGE request can be used to carry the instant message. This is sometimes called page mode, because each instant message is not related to other instant messages. When it is desirable to establish a session of instant messages, SIP can be used to establish a session and MSRP is used to carry the actual instant messages within that session. This can be useful for users who are trying to follow the flow of a conversation, because the relation between instant messages can identify them as corresponding to a given conversation.
When a user A sends a SIP instant message to user B, and B is offline, the message is conventionally stored in an application server. Previously there was not a mechanism whereby the user could retrieve the user's stored messages without missing important bits of information (sender, date/time, session, and the like). In earlier solutions if the sender used SIP to send messages to a user who is offline, the actual contents of the instant messages were stored in a store message application server. Subsequently, when the recipient was online and used MSRP to retrieve the stored messages, the recipient got the actual instant messages but did not get the identity (for example, SIP URI) of the sender, nor the date/time information when the message was sent.
Additionally it was not possible for the recipient to distinguish between messages belonging to a SIP session of instant messages and those messages deposited in the store message application server by using SIP MESSAGE requests. This occurred because the identity (e.g., SIP URI) of the person who deposited the message in the store message application server was only present in the SIP requests. When the text of the message was stored, the header information was not retained. Moreover, the MSRP headers do not contain any relation to or indication of those SIP headers.
Various conventional systems exist for retrieving deferred messages. For example, a time stamp can be added to the stored messages by an instant messaging service. SIP or MSRP can be used to retrieve the stored messages. It has been proposed that if messages contained metadata, the user could better manage deferred instant messages. However, no realistic solutions have been provided.